Process for retouching of subtractive multicolor images



Patented Apr. 13, 1943 PROCESS FOR RETOUCHING OF' SUBTRAC- TIVEMULTICOLOR IMAGES Wilhelm Schneider. Dessau, and Gustav Wilmanns,Wolfen, Kreis Bittc'rfeld, Germany, as-

signors to General Aniline & Film, Corporation, New York, N. Y., acorporation of Delaware No Drawing. Application January 18, 1940, SerialNo. 314,448. In Germany January 18, .1939

1 Claim.

This invention relates to the retouching of photographic subtractivemulticolor images. In

some cases it is desirable to retouch subtractive multicolor images,obtained for instance by color development of a plurality of silverhalide emulsion layers, in order to remove wrong color tinges .or colorspots. also in order to correct the color value of certain objects whichthough objectively correct, are not satisfying, from an aesthetical viewpoint. For that purpose a great number of various dyestuffs arenecessary in order to meet tage that the dyestuffs react under theinfluence of light or chemicals in exactly the same way as the imagedyestuffs, so that, if changes occur caused by chemicals or light, theretouching the needs of every case. Some dyestuffs however possess sucha small spectral range, that it is impossible, to predict, how theretouching dye-, stufis will show together with the dyestuffs of theemulsion layer. This is especially true in reflected 'light, forinstance with paper images, where reflection-color andtransparency-color are .mixed together inextricably. A dyestuif forinstance, the maximum of which lies at about 600-650 m and which is ofblue color, will never form green together with the yellow dyestufisalready in the emulsion layer, but will yield only blackish colorvalues.

It has been found that'these difficulties can be absolutely avoided, iffor retouching subtracand blue color values;

tive multicolor images, especially on multicolor photographic material,dyestuffs are usedwhich correspond completely or approximately in regardto their spectral absorption to the image dyestufls in the emulsionlayers produced therein by color development and which are. taken up bythe photographic layers in a transparent form.

The absorption maxima of the'retouching dyestuffs corresponding to theimage dyestuffs lie in a region of about 450 m for yellow, 550- m forpurple and 6'70 mp. for red. Also mixtures may be prepared from thesedyestuffs for red, green Furthermore dyestuffs never becomes visible.Furthermore when dyestuffs of the same absorption as the image dyestuifsare used, the general impression of the multicolor image remains thesame in daylight as in artificial light.

. The subtractivemulticolor images to be retouched according to this.invention may be obtained by different processes, for instance bycolored development according to U. S. Patents 2,178,612, 2,179,228,2,179,239, 2,179,244 and 2,186,849.

If the image dyestuffs in the emulsion were I obtained by colordevelopment from difiusionfluence color, color-fastness or stabilitytowards may be used with two absorption maxima corre-' spending to thoseof the dyes in the emulsion layers.

Suitable dyestufisfor retouching may be found in nearly all dyestuifgroups, for instance azodyestuffs. especially for yellow and purplecolor tones, the xanthene-dyestuffs, triphenylmethane-dyestufis,oxazines, thiazines and azines which'yield particularly ,purple andblue-green color tones.

It is advisable to use for retouching, dyestuffs with the sameconstitution as those in the emulsion layers used for building up thecolor image. This conformity may be complete or restricted to theauxochrome groups. This ha the advanfree dyestuil components, it is notonly unnecessary', but even undesirable to use a retouching dye'stufiwith aradical of difiusion-free characteristics, since such a dyestuilcannot penetrate into the colloidal layer .and consequently will causesplotches. t

To substitute the retouching dyestuffs with groups of littlesignificance or to omit a substituent existing in the dyestuffs of theemulsion layers, is immaterial, as long as it does not inchemicals.

The process of the present invention is suitable for the retouching ofnegative and positive images as transparencies and in. reflected lightand also paper images.

Example I A blue retouching dyestufi is obtained in the followingmanner: of 8. mol of u-hydroxynaphthoic acid and 28 grams of sodiumhydroxide are dissolved in-100 cc. of Water. To this solution of 9. molof diethyl-p-phenylendiaminehydrochloride in water is added. Whilecooling ,and stirring of a mol of potassium ferricyanide is slowlyadded. After a short time the dyestufi crystalliz'es in fine needles.The precipitation is completed by adding a saturated solution of commonsalt. The dyestufi is then sucked 011 and purified by extraction withmethanol. Deep-dark crystals with purple surface luster are obtainedwhich are soluble in water with'blu color.

Example II A yellow retouching dyestuff is obtained in the Y followingmanner: of a; mol of m-aminobenzoylacetanilide-p-carboxylic acid is condensed with diethyl-p-phenylendiamine in the same way as described inExample I. An ocher colored dyestufl powder is obtained which is solublein water with a yellow color.

Example III a a diffusion-free derivative of m-aminobenzoybacetanilide-p-carboxylic acid, in the green sensitized layer adiffusion-free derivative of 1-5- naphthyl 3 methyl-S-pyrazolone -4,8'-disulfo acid and in the red sensitized emulsion layer a diffusion-freederivative of e-hydroxynaphthoic acid.

We claim:

In a process for retouching photographic subtractive multi-color imageson photographic multi-layer material wherein said images compriseyellow, magenta and blue-green color developeddyes, the image dyestuifscontaining in their molecule at least one radical effecting fastness todiffusion, the improvement which comprises the use of transparentretouching dyestu s exhibiting a spectral absorption correspondingsubstantially to that of said image dyestmr's and containing in theirmolecule auxochrome groups corresponding to those of one of said imagedyestufis and no radical effecting fastness to diffusion said dyestuiffor retouching the blue-green image layer being the reaction product ofa-hydroxy naphthoic acid with the oxidation products ofdiethyl-p-phenylendiamine, said dyestufi for retouching the magentaimage layer being the reaction product of1-pnaphthyl-3-methyl-pyrazolone-4 8-disulfo acid with the oxidationproducts of diethyl-p-phenylendiamine and the dyestufi for retouchingthe yellow image layer being the reaction product ofm-aminobenzoylacetanilide-p-carboxylic acid with the oxidation productsof dIethyL-p-phenylendiamine.

WILHELM SCHNEIDER. GUSTAV WIIMANNS.

